public class Test {
    public static void main(String[] args) {
        SingList singList = new SingList();
        singList.addLast(1);
        singList.addLast(2);
        singList.addLast(3);
        singList.addLast(4);
        singList.removeAllKey(1);
        singList.clear();
        singList.display();
        System.out.println(singList.size());
        System.out.println(singList.contains(1));
        System.out.println(singList.contains(2));
        System.out.println(singList.contains(3));
        System.out.println(singList.contains(4));
        System.out.println(singList.contains(5));
    }
}
